function getxmlhttp() {
	var xmlhttp;
	if(window.XMLHttpRequest) { // code for IE7+, Firefox, Chrome, Opera, Safari
		xmlhttp = new XMLHttpRequest();
	} else { // code for IE6, IE5
		xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
	}
	return xmlhttp;
}

function ajax(type, url, xmlhttp, fn) {
	xmlhttp.onreadystatechange = fn;
	xmlhttp.open(type, url, true);
	xmlhttp.send();

}